Some Martian Lakes Formed Much Later Than We Expected

A team of researchers led by Sharon Wilson, from the Smithsonian Institution and the University of Virginia, discovered that lakes and streams continued to flow on the Red Planet for over a billion years after a well-documented era of wet conditions. This finding could be crucial in our understanding of Mars and the potential for life there.

"We discovered valleys that carried water into lake basins," said Wilson in a statement. "Several lake basins filled and overflowed, indicating there was a considerable amount of water on the landscape during this time.”

The findings, reported in the Journal of Geophysical Research Planets, discuss stream-flows and associated lakes that could have been seasonal. They estimated the age of the region by looking at the number of craters and if the water features were there before or after the impacts.

The team estimated that these valleys and lakes were formed between 2 and 3 billion years ago, long after Mars is believed to have lost its atmosphere and become cold. Although the finding indicates flowing water, this is consistent with a frozen Mars.

"The rate at which water flowed through these valleys is consistent with runoff from melting snow," Wilson said. "These weren't rushing rivers. They have simple drainage patterns and did not form deep or complex systems like the ancient valley networks from early Mars."

These types of valleys appear in vast mid-latitude regions both north and south of the equator. These shallow valleys were part of a global cycle of water rather than a local system.

Our exploration of Mars requires understanding of the geological epochs of the Red Planet and how water shaped this now inhospitable environment. A lot of clues point to a water-rich world in the distant past, and perhaps it was like this long enough for some lifeforms to evolve.